How Monkeys Use a Toothbrush

Here's your nightly math! Just 5 quick minutes of number fun for kids and parents at home. Read a cool fun fact, followed by math riddles at different levels so everyone can jump in. Your kids will love you for it.

How Monkeys Use a Toothbrush

Imagine being so tiny that you use a toothbrush to comb your hair. That’s life for this very, very tiny monkey, a pygmy marmoset named Ninita who was rescued from the jungle. All marmosets are small: in fact, their name comes from the French word for shrimp. And the word pygmy means really, really small. Pygmy marmosets reach a height of 6 inches at most; that’s shorter than the length of a grown-up’s hand. They weigh only about 5 ounces, about the same as a few candy bars. To eat, these teeny monkeys sink their teeth into trees and suck out the sap. They can put 1,300 holes in a single tree! So Ninita may need that toothbrush for her teeth, too.

Little kids: If Ninita is just 5 inches long but her tail is 8 inches long, how much longer than her tiny body is her tail? Bonus: How long are she and her tail together from end to end?

Big kids: If a crowd of pygmies bites 200 holes into a tree each week, how many holes do they make in a 4-week month? Bonus: If the San Diego Zoo buys 38 toothbrushes and uses half of them to brush the monkeys, how many do they use in that weird way?

Answers:Wee ones: The glass!

Little kids: 3 inches longer. Bonus: 13 inches.

Big kids: 800 holes. Bonus: 19 toothbrushes.

About the Author

Laura Bilodeau Overdeck is founder and president of Bedtime Math Foundation. Her goal is to make math as playful for kids as it was for her when she was a child. Her mom had Laura baking while still in diapers, and her dad had her using power tools at a very unsafe age, measuring lengths, widths and angles in the process. Armed with this early love of numbers, Laura went on to get a BA in astrophysics from Princeton University, and an MBA from the Wharton School of Business; she continues to star-gaze today. Laura’s other interests include her three lively children, chocolate, extreme vehicles, and Lego Mindstorms.